Anomalous Intensification of a Turbulent Separated Flow in Inclined, Single-Row, Oval-Trench Dimples on the Wall of a Narrow Channel

摘要

In a long, plane-parallel channel with single-row, inclined, oval-trench dimples on the wall, a periodic section with a relative length of 8 (the distance between centers of neighboring dimples), a width of 9, a height of 1, and a centrally located, inclined, oval-trench dimple with a length of 7.05, a width of 1.05, a depth of 0.25, and with variation in the inclination angle from 1 degrees to 89 degrees is considered. An anomalous intensification of a separated turbulent air flow in an inclined dimple at the Reynolds number of 10(4) is discovered. At an inclination angle of 60 degrees, the maximum absolute value of negative friction in the middle longitudinal cross-section exceeds the friction in a plane-parallel channel by more than 2.5 times. The cause of this phenomenon is related to the formation of a high pressure drop between the closely located zones of stagnation and low pressure in the semispherical inlet segment of the dimple.